21-25 August 2012

Portorož, Slovenia

UTC timezone

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48

Type: Oral presentation

Several optimization techniques have been developed in the past for optimizing various real-life problems we encounter during logistic operations. The quality and applicability of the results depend on the quality of input data as the famous saying "garbage in - garbage out" applies here more than anywhere. With input data we consider here quality of digital maps, accessibility and quality of GPS
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Presented by Dr. Alen ORBANIć

Type: Oral presentation

Association schemes are background combinatorial objects
in the area of Algebraic Graph Theory (AGT).
The main well-known origin of models for association schemes,
the so-called Schurian association schemes,
appears from transitive permutation groups
by taking their 2-orbits (orbitals). All association
schemes of order up to 14 can be obtained in this manner.
It turns out that not all asso
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Presented by Dr. Štefan GYüRKI

Type: Oral presentation

House of Graphs (http://hog.grinvin.org) is a searchable database of graphs. It offers lists of graphs and generators but also a special list of graphs that turned out to be interesting or relevant in the study of graph theoretic problems or as counterexamples to conjectures. A prototype of this project was first presented in the previous edition of CSD (Computers in Scientific Discovery 5, Sheffi
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Presented by Prof. Hadrien MéLOT

Type: Oral presentation

An $n\times n\times n$ cube is made from $n^3$ unit cubes. Two such
cubes are neighbours if they touch along a face. In each step of a
dismantling process, we may remove a small cube that has precisely
three neighbours. A move is {\it balanced} if the three neighbours are in three orthogonal directions.
In the extremal case, there are $n^2$ independent small cubes left at the end of the d
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Presented by Dr. Janos BARAT

Type: Oral presentation

Carbon cages which violate the isolated pentagon rule or have an open-shell electronic system can be stabilized to be isolable by an appropriate endohedral or exohedral functionalization. Such an example is the observation of the C28 cluster with Td symmetry with an encapsulated uranium atom. A systematic study of classical fullerenes, i.e. containing only pentagons and hexagons, with tetrahedral
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Presented by Dr. Levente Csaba NAGY

Type: Oral presentation

This talk will discuss the construction and classification of configurations by computers. Results and conjectures will be presented.
An early result was obtained for cubic graphs on 10 vertices (which were needed for applications in chemistry) in the 1960s by Balaban and Imrich. The same result had already be obtained at the end of the 19th century in the language of configurations, of course wi
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Presented by Harald GROPP

Type: Keynote Lecture

An arc is a set of points in a projective plane with the property that no three of them are on the same line. An arc is called complete if no point can be added to it so that it still remains an arc. The conic serves as the standard example of a complete arc, but many other constructions are known.
Although arcs are relatively small (at most q+2 points in a finite projective plane of order q an
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Presented by Prof. Kris COOLSAET

Type: Oral presentation

Cloud computing is fundamentally changing how computing resources are being delivered. The end-users increasingly access cloud-based applications using remote web-services, standard web browsers or “native applications” that just pretend to be more than a web browser. Infrastructure, databases and software are being deployed in a way that can be used as a service (rented) when needed. At the s
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Presented by Dr. Boris HORVAT

Type: Oral presentation

In the simplest case, a geometric $(n_k)$ configuration is a set of $n$ points and $n$ lines such that each of the points is incident with precisely $k$ of the lines and each of the lines is incident with precisely $k$ of the points. Instead of lines, the second subset can consist of planes, hyperplanes, circles, ellipses, etc. We present some new classes of highly symmetric spatial point-line co
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Presented by Dr. Gábor GéVAY

Type: Keynote Lecture

One of the promising fields in linguistics deals with the 'meanings' of sentences and words. In the present talk two cases will be discussed to show how various computer methods can be applied to the linguistic problems. The first case shows is the use of Kohonen Self-organizing maps- SOM (a special method of Artificial neural networks (ANNs) for studying and comparison of different styles of writ
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Presented by Prof. Jure ZUPAN

Type: Keynote Lecture

The standard model of molecule (on the topological level of abstraction) is an unlabeled colored multigraph, expressing by its nodes the atoms, by its (multiple) edges the covalent bonds. The nodes are colored by atom names and states. But there are problems, the model expresses pairwise interactions only, so the notion of aromaticity shows that it should be generalized, maybe to a hypergraphic mo
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Presented by Prof. Adalbert KERBER

Type: Oral presentation

Coherent configurations (Higman, Weisfeiler-Leman) are a central
notion in Algebraic Graph Theory. An important class of coherent
configurations - the so-called Schurian configurations - are obtained
from the 2-orbits of permutation groups of finite degree. However in
general, coherent configurations are non-Schurian.
Important invariants of coherent configurations are their types; they
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Presented by Dr. Sven REICHARD

Type: Oral presentation

We show that if an $n$-edge cut divides a graph into two subgraphs, then the Tutte polynomial of the original graph can be fully expressed by Tutte polynomials of these parts. We give a formula consisting from a determinant of size $1+b_{n}$ (where $b_{n}$ is the $n$th Bell number). The edge cut induces a bipartite graph with partition of vertices of size $p$ and $p'$. Our second formula uses dete
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Presented by M. KOCHOL

Type: Oral presentation

There are nowadays many automated systems [3] helping researchers in graph theory, such as Graffiti (1987) [2], AutoGraphiX (AGX) (2000) [1] and Graphedron (2008) [4]. However, no system has been developed for directed graphs. Moreover, as most of existing systems use exact (and costly in time) algorithms, new approaches are needed.
We introduce here <i>Digenes</i>, a new tool for directed extr
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Presented by Mr. Romain ABSIL

Type: Keynote Lecture

The traditional allotropic forms of carbon, multilayer graphene and diamond, are “honorary hydrocarbons” with huge numbers of carbon atoms surrounded by a negligible number of hydrogen atoms. Enumerations of benzenoids should consider both definitions, including or excluding helicenes. Dualists offer simple classifications for catafusenes, perifusenes, and coronoids as having acyclic, triangul
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Presented by Prof. Balaban ALEXANDRU

Type: Poster

Purine, as a mother template of important nucleobases, is the good model system to study such properties of these systems as pi-electron delocalization and interactions with acidic or basic partners. For this purpose, modeling of equilibrium H-bond formation of the types N…HF and NH…F– was used [1].
H-bonded complexes of purine (four complexes for each tautomer: 1-H, 3-H, 7-H and 9-H puri
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Presented by Dr. Halina SZATYLOWICZ

Type: Oral presentation

We describe a new algorithm for the efficient generation of fullerenes. The algorithm generates all non-isomorphic fullerenes using the construction operations from [1]. We will describe the construction, provide details on the way isomorphism rejection is handled, and give some optimizations. Our implementation of this algorithm is more than 3 times faster than previous generators for fullerenes.
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Presented by Mr. Jan GOEDGEBEUR

Type: Oral presentation

Encyclopedia of Graphs (http://atlas.gregas.eu/) is an online encyclopedia of graph collections aiming to help researchers find and use data about different families of graphs. It has been created as a part of the ESF funded GreGAS project with the goal of becoming a general reference and repository of graphs and graph-like structures offered to all scientists and researchers for use and to provid
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Presented by Dr. Primož LUKšIč

Type: Oral presentation

A Delaney-Dress symbol is a structure that encodes an equivariant tiling, i.e. tilings together with their symmetry groups. In this talk we will describe a generator for Delaney-Dress symbols and thus for tilings. We will give an introduction to Delaney-Dress symbols and discuss the structural properties that are used by the generation algorithm. We will also present some results already obtained
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Presented by Mr. Nico VAN CLEEMPUT

Type: Oral presentation

We investigate the structure of trees that have minimal $k$-th Laplacian and Dirichlet Eigenvalues among all trees with a given degree sequence.

Presented by Dr. Matjaž KOVšE

Type: Keynote Lecture

The concept of communicability between pairs of nodes in a graph is introduced. Then, the communicability distance is defined and it is proved that it corresponds to a Euclidean distance in the graph. The mathematical expressions for the communicability distance between pairs of nodes in paths, cycles, stars and complete graphs are obtained as well as the expressions for the sum of all distances i
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Presented by Prof. Estrada ERNESTO

Type: Oral presentation

1. Introduction
An interesting aspect of finite-length carbon nanotubes (CNTs) is the quantum finite-size effects of the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). It has been shown that the HOMO-LUMO gaps in the zigzag CNTs show the oscillation depending on the number of hexagons around the peripheral circuits. We have sh
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Presented by Dr. Noriyuki MIZOGUCHI

Type: Oral presentation

A {\it fullerene} is an all carbon molecule that can be represented
by a $3$-regular planar graph with face sizes five or six.
A subset $S$ of the vertices of a graph forms an
{\it independent set} if the vertices of $S$ are pairwise
non-adjacent. This talk describes chemical applications for
independent sets of fullerenes and algorithms for generating them.

Presented by Dr. Wendy MYRVOLD

Type: Poster

For a graph $G=(V,E)$, \emph{a Roman dominating function} (RDF) is a function $f \colon V \to \{0,1,2\}$ satisfying the condition that every vertex $u$ for which $f(u)=0$ is adjacent to at least one vertex $v$ for which $f(v)=2$. The weight of an RDF equals $w(f)=\sum_{v\in V}f(v)=|V_1|+2|V_2|$. An RDF for which $w(f)$ achieves its minimum is called \emph{a} $\gamma_R$\emph{-function} and its weig
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Presented by Ivona PULJIć

Type: Keynote Lecture

How many large eigenvalues can a graph have? An answer depends on the interpretation of what it means for en eigenvalue to be large. This question and some related problems in extremal algebraic graph theory will be discussed.

Presented by Bojan MOHAR

Type: Poster

Aromaticity is an important and widely used concept characterizing properties and structure of many organic and inorganic chemical compounds [1–3]. Environmental effects can lead to significant structural alterations of molecules directly exposed to environment. Such changes are of particular interest in molecules important from a biochemical perspective. All nucleobases and four amino acid res
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Presented by Dr. Beata SZEFLER

Type: Keynote Lecture

Aromaticity is an elusive chemical concept, with many definitions, but it does have at least one clear manifestation in ‘ring currents’ induced in planar unsaturated molecules by perpendicular magnetic fields. Efficient ab initio calculation of such currents is now a practical possibility. The resulting current-density maps allow us to visualise aromaticity and to develop interpretations and t
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Presented by Prof. Patrick FOWLER

Type: Oral presentation

Molecular dynamics calculations can reveal the physical and chemical properties of various carbon nanostructures or can help to devise the possible formation pathways.
In our days the most well known carbon nanostructures are the fullerenes and the nanotubes. They can be thought of as being formed from graphene sheets, i.e. single layers of carbon atoms arranged in a honeycomb lattice. Usuall
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Presented by Dr. Istvan LASZLO

Type: Poster

Mathchem is a free open source Python package for calculating topological indices and other invariants of molecular graphs.
For performance reasons we use here concept of lazy calculations. This means that we calculate data only when it is needed and then we save the results.
Mathchem can be installed either as Python or as Sage module.
Since the package contains no compiled code it is cross-pl
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Presented by Mr. Alexander VASILYEV

Type: Oral presentation

The minimum genus problem is a classical, but NP-complete problem in
topological graph theory. Minimum genus of cartesian products is closely
related to the minimum genus of a group, the minimum among genera of all
Cayley graphs of the given group. For abelian groups, the most difficult
case arises when the group contains a Z_3 factor in its canonical
decomposition. In this talk we focus main
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Presented by Michal KOTRBčIK

Type: Oral presentation

In chemical graph theory a topological index is a molecular descriptor that is calculated on the basis of molecular graph of a chemical compound. They are used for example in QSAR approach in which the biological activity of molecules is correlated with their chemical structure.
The bibliographic data on topological indices were obtained from Web of Science, an online citation database for scient
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Presented by Jernej BODLAJ

Type: Oral presentation

The Zentralblatt MATH Database stores metadata about mathematical papers and books. It is maintained by the Berlin editorial ooffice of FIZ Karlsruhe in cooperation with European academies and mathematical institutes. We analyzed the ZB data about scientific works published within the period 1990 to 2010.
The raw data were converted into four 2-mode networks: works x authors, works x journals,
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Presented by Ms. Monika CERINšEK

Type: Oral presentation

In approximation theory, it is well known that the bivariate polynomial interpolation problem at domain points of a triangle is correct. Thus the corresponding interpolation matrix M is nonsingular. L.L. Schumaker stated the conjecture, that the determinant of M and all principal minors of M are positive. This result would solve the constrained interpolation problem.
In this talk, the basic con
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Presented by Mr. Tadej KANDUč

Type: Keynote Lecture

Graphs can be drawn in an infinite number of ways. However, by analysis of eigenvectors of adjacency and Laplacian matrices of molecular graphs one is able to get drawings which reproduce rather well geometries in some classes of molecules like fullerenes, nanotubes and their junctions. The results obtained up to now will be discussed and possible new routes to generalize graph drawing techniques
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Presented by Prof. Ante GRAOVAC

Type: Oral presentation

We present a new parallelized algorithm, Parallel-ProBiS, for detecting similar binding sites on clusters of computers. This is a new algorithm that calcu- lates the local similarity metric between protein structures, and is especially suited to efficient execution on multiple CPUs. The obtained speedups of the parallel ProBiS scale almost ideally with the number of computing cores up to about 64
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Presented by Ms. Kati ROZMAN

Type: Oral presentation

POLYBENZENES AND RELATED NANOSTRUCTURES
Mircea V. Diudea
“Babes-Bolyai” University, Faculty of Chemistry and Chemical Engineering,
Arany Janos Str. 11, 400028, Cluj, Romania
diudea@gmail.com
Abstract. Polybenzene BTA_48 (Figure), designed by map operations, can dimerize either by identification of octagons R(8) to provide a diamond-like fcc-net or by identifying the “opening
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Presented by Prof. Mircea DIUDEA

Type: Oral presentation

A \emph{combinatorial configuration} $(v_r, b_k)$ is an incidence structure with $v$ points and $b$ blocks (called lines) such that each point is incident with $r$ lines, each line is incident with $k$ points and two distinct lines are incident with at most one common point. When $v = b$ (and consequently $r = k$) we speak of \emph{symmetric} or \emph{balanced} $(v_r)$ configurations.
One of th
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Presented by Mr. Marko BOBEN

Type: Keynote Lecture

Chemical Graph Theory is concerned with analysis of chemical data using Discrete Mathematics and Graph Theory. Graphical Bioinformatics approaches problems of Bioinformatics by representing input data graphically and follows with their numerical analysis. We will consider recent developments in these areas including: (1) Novel graph matrices and novel graph invariants; (2) Graph theoretical calc
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Presented by Prof. Milan RANDIć

Type: Keynote Lecture

A Latin square of order $n$ is an $n\times n$ matrix containing $n$
different symbols (often the numbers $1,\dots,n$), positioned in such
a way that each symbol occurs exactly once in each row and exactly
once in each column. Latin squares have numerous applications in
design of experiments, schedules for sporting tournaments, codes for
communication and so on. In this talk I will consider, f
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Presented by Ian WANLESS

Type: Keynote Lecture

Fluency in a language is fundamental to an understanding of any culture and the struggle to develop the language of the Sciences, mathematics and related symbolism, proved to be unnaturally difficult. In fact Science was born around the time of the 16th Century as a consequence of a new philosophical approach which required evidence for the validation of all claims without exception. This way of
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Presented by Prof. Harold KROTO

Type: Keynote Lecture

In this talk I will sketch an algorithm to generate Snarks -- that
is cubic cyclically 4-connected graphs with chromatic index 4.
Snarks are especially interesting as for several conjectures it can be shown that if they wrong, the smallest counterexample is a Snark.
I will also give some examples of conjectures that were refuted with the lists generated by the algorithm.
As we are now able
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Presented by Gunnar BRINKMANN

Type: Keynote Lecture

Community detection is an important part of the analysis of naturally occuring networks. The quality of division into communities is measured mostly by modularity, representing the difference from the expected number of edges occuring within and between the communities. Here we reinterpret modularity within a more general framework for measuring the quality of community division and discuss on rea
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Presented by Prof. Dragan STEVANOVIć

Type: Keynote Lecture

\begin{abstract}
\noindent Many Problems in Computational Geometry and geometric
Graph Theory are based on the most simple geometric objects: points
in the plane and straight line segments connecting them. Moreover,
for most combinatorial questions in this area only the ``discrete''
properties of the underlying point set have to be considered. More
precisely, the crossing prop
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Presented by Prof. Oswin AICHHOLZER

Type: Keynote Lecture

Molecular stability and electronic degeneracy do not form an evident combination. In degenerate states of highly symmetric molecules, there is a mismatch between the symmetries of electronic and nuclear charge distributions. This imbalance gives rise to a spontaneous distortion of the nuclear frame to a lower symmetry, which lifts the degeneracy. The effect is known as the Jahn-Teller (JT) effect.
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Presented by Prof. Arnout CEULEMANS

Type: Oral presentation

A matrix $A \in \mathbb{R}^{n \times n}$ is a Euclidean distance matrix (EDM) if there exist points $x_1, x_2, \dots, x_n \in \mathbb{R}^d$, such that $a_{ij} = ||x_i - x_j||^2$.
The minimal possible $d$ is called the embedding dimension.
A well known result states that the rank of an EDM is $d + 2$ for the points in a general position, and $d + 1$ if the points lie on a $d - 1$ dimensional hype
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Presented by Dr. Iztok KAVKLER

Type: Oral presentation

The Hückel–London–Pople–McWeeny (HLPM) (‘Topological’) approach1–4 for calculating π-electron ring-currents and bond-currents in conjugated systems is applied to a series of structures that have been called ‘super-ring’ molecules5. These consist of an outer ring of carbon atoms (of perimeter length either [4n] or [4n+2]) connected by internal C–C bonds to an inner, central ring
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Presented by Dr. Roger MALLION

Type: Poster

In this work we investigate the problem of numerical characterization of two dimensional proteomics maps based on construction of Voronoi regions. To enable for the taking into account of the concentrations of proteins on the proteomic map, we have used the process which gives greater weights to spots representing proteins with greater abundance. As we have shown, the shapes of the resulting Voro
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Presented by Rok OREL

Type: Oral presentation

In 1845, as a 21-year-old undergraduate, Gustav Robert Kirchhoff (writing under the pseudonym ‘Studiosus’ Kirchhoff) published, as ‘Mitglied des physikalischen Seminars zu Königsberg’ at the Albertina University, a classic paper1 in which he stated his Laws I and II of electrical circuits — laws which, for more than a century, have been ‘well-known to every schoolboy’. Two years la
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Presented by Dr. Roger MALLION